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一张原型图片上添加一行带背景的文字。使用Row Widget或者Column Widget是实现不了的,这时就需要使用Stack Widget,也就是层叠布局来实现了。
直接上代码:import 'package:flutter/material.dart';void main() => runApp(MyApp());class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Layout Widget', home: Scaffold( appBar: AppBar( title: Text('Stack Widget'), backgroundColor: Colors.deepPurple, ), body: Center( child: Mystack(), ), ), ); }}class Mystack extends StatelessWidget { @override Widget build(BuildContext context) { return Stack( children:[ CircleAvatar( backgroundImage: NetworkImage( 'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1554199381&di=e3a6604c718d6304e4912f5a7d8e6d2f&imgtype=jpg&er=1&src=http%3A%2F%2Fimg.11665.com%2Fimg1_p3%2Fi3%2F1918445441%2FTB20kv.dlDH8KJjSszcXXbDTFXa_%21%211918445441.jpg'), radius: 100, ), Container( child: Text( '盲僧—李青', style: TextStyle(fontSize: 18, color: Colors.white), ), decoration: BoxDecoration(color: Colors.blueAccent), padding: EdgeInsets.fromLTRB(5.0, 0, 5.0, 0), ) ], alignment: const FractionalOffset(0.5, 0.9), ); }}
代码分析:
Mystack
类返回的组件就是Stack()
,它同样需要一个组件数组。这里我们使用了CircleAvatar
和Container
。(,) CircleAvatar
组件经常用来作头像控件,组件里边有个radius的值可以设置图片的弧度。
CircleAvatar( backgroundImage: NetworkImage( 'url'), radius: 100,),
alignment: const FractionalOffset(0.5, 0.9),
如果超过两个组件的层叠,alignment属性就满足不了需求了,需要使用Positioned属性。所以这个组件也叫做层叠定位组件。
class Mystack extends StatelessWidget { @override Widget build(BuildContext context) { return Stack( children:[ CircleAvatar( backgroundImage: NetworkImage( 'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1554199381&di=e3a6604c718d6304e4912f5a7d8e6d2f&imgtype=jpg&er=1&src=http%3A%2F%2Fimg.11665.com%2Fimg1_p3%2Fi3%2F1918445441%2FTB20kv.dlDH8KJjSszcXXbDTFXa_%21%211918445441.jpg'), radius: 100, ), Positioned( top: 20.0, left: 50.0, child: Container( child: Text( '盲僧—李青', style: TextStyle(fontSize: 18, color: Colors.white), ), decoration: BoxDecoration(color: Colors.blueAccent), padding: EdgeInsets.fromLTRB(5.0, 0, 5.0, 0), )), Positioned( child: Text( '文本组件', style: TextStyle(color: Colors.white, fontSize: 18), ), bottom: 10, right: 60, ) ],// alignment: const FractionalOffset(0.5, 0.9), ); }}
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